With the rapid increase of the amount of information, the amount of data stored in storage systems increases significantly. Service developments also impose higher requirements upon data processing technologies with respect to availability, reliability and expandability, in which data safety is of particular importance. The existing major technologies used for data protection include making backups and taking snapshots of the data. A snapshot is a completely usable copy taken from a data object. The copy includes an image of the data object at a certain time instant. Currently, there are three major snapshot technologies: Virtual Snapshot, Split Imaging and Copying on Demand.
With a snapshot technology, data stored in a source Logical Unit Number (LUN) may be obtained at an instant and occupies a small storage space. Snapshot technologies are relatively mature for the real time protection of data. There are three snapshot technologies in use currently. One is taking snapshots manually by a user. Another one is taking snapshots in connection with other operations (LUN copying, remote imaging). A further one is to take timed snapshot. In the three snapshot technologies, timed snapshot technology is one with which snapshots of a specified source LUN are taken automatically by the system in a certain time interval.
It is found by the inventor in the realization of the present invention that the related art technologies have the following defects:
The existing mode for the usage of automatic snapshot has only a single technology of timed snapshot, i.e. snapshot periodically: the snapshot for the current time instant is automatically taken by the system in a specified time period. The mode of automatic snapshot invocation has only a timed mode, which is relatively singular, and has limitations in some cases. For example, snapshots may still be taken for data even when no or little change is made to the data in the time period, causing unnecessary wasting of system resources.